Study On Integrate Treatment Of Printing And Dyeing Wastewater Of Textile Industry

The production engineering of printing and dyeing of textile industry mainly includes destarch, seethe, bleaching, mercerization, dyeing, printing, marshal and etc. A large quantity of wastewater come from textile industry in China has the high-strength chroma and other organics, which badly threaten the natural environment. Most polluting of these kinds of wastewater of textile industry is printing and dyeing wastewater.Many researches are keen on dealing with printing and dyeing wastewater of textile industry. Main techniques of handling include chemical methods, physical methods, biotechnological methods, and heat treatment methods. The main processing of disposition covers into pretreatment and after-treatment. With the development of science and technology more kinds of dye are applied in textile industry, and most of these dyestuffs have the characteristics of anti-oxidation, anti-photodecomposition, high-strength COD and chroma. All these make the deposition of dyeing wastewater more and more difficult.Under the laws of environmental protection and resource protection, recycle of water resource and some useful material became more important in research. Under all these backgrounds a lot of advanced methods and techniques are used in the deposition of wastewater. In this paper a novel and advanced engineering progress in printing and dyeing industry wastewater combined with methods of flocculation, nanofiltration and biotechnology is generated.This thesis consists of three parts. The first part includes the second chapter and the third chapter, mainly discussing the pretreatment of wastewater by flocculation; The second part mainly discusses after-treatment of wastewater by nanofiltration, In this part separations of performance of membrane in dye-water and salt-water system are illustrated in detail. After illustrating the characteristics of membrane the paper goes on sequentially studies the performance of treatment of textile wastewater. The nanofiltration progress is sure to produce concentrate, which will be dealt with anaerobic biotechnology, this process will discussed in the third part of this paper at length.In the first chapter, current situation of textile wastewater and dominating methods in treatment is dissertated first. Then the primary mechanism of these methods is illustrated. The second chapter discusses the method of flocculation in treating wastewater by high efficiency flocculant. This high efficient decolourant ispolymerized by dicyandiamide and formaldehyde namedDicyandiamide-Formaldehyde. In the optimum condition of the operation decoloring rate can achieve above 98% and rate of COD removal may reach above 70%. The third chapter discusses further built flocculation composed by high efficiency decolourant and current flocculation. At the result of chapter two and experimentation of orthogonal table get the result that main effect factor is pH and adding amount of PAC and MgC^. This work sequentially researches the optimum scale of Dicyandiamide-Formaldehyde, PAC and MgC^ by center response curve. At the optimum condition decolor rate can reach above 99.9% and rate of COD removal can reach above 90%. Pretreatment of flocculation progress greatly lighten the load of after-treatment. The forth chapter researches some basic character of nanofiltration membrane and its performance in separation of dye-water system, in the result of this chapter we can find that nanofiltration membrane can not only separate dye and water efficiency but has litter retention of salt. The fifth chapter studies the nanofiltration membrane used in wastewater separation in some conditions, just as pH, temperature, pressure, concentration and flux. The results show that nanofiltration membrane used in experiment has good performance, the rate of decolor can be 100% and efficiency of COD removal can reach above 93%. The permeate water treated by nanofiltration progress can achieve criteria of industry. The sixth chapter studies the treatment of concentrate by an series connection of denitrification and aerobic reaction. COD of concentrate is between 1500-5000, at optimum condition (37 °C, pH=7, 24h, COD:N:P=300:5:1) of denitrifying of anaerobic COD can fall to 50% of initializing value, after anaerobic progress is aerobic progress, in this status COD can fall to 485 mg/L in 24h. After treatment of biological progress this wastewater can return to pretreatment or nanofiltration progress.